In a typical hybrid electric vehicle (HEV), a high powered battery supplies power to the hybrid drive train containing electric motors. Under heavy load conditions, the high powered battery can supply additional energy to augment the energy supplied through the vehicle's internal combustion engine, thereby improving performance. The battery can then be recharged during lighter load conditions, or charged from energy generated during vehicle deceleration. Due to the high power restraints placed on the battery, it must maintain a state of charge (SOC) within a narrow operating range to ensure long life. Also, a buffer below full charge of the battery must remain to allow energy to be recaptured when the vehicle decelerates while the battery is “fully charged.” Consequently, a shortcoming of this typical HEV system is that the maximum capacity of this battery can never be fully utilized for vehicle propulsion.
More than one power source may also be used to provide power to the vehicle. For example, a high power battery pack may be used in unison with a high capacity battery pack in order to provide both high capacity and high power. Also, a solar panel may be used alongside a battery pack in order to capture the energy production capabilities of the solar panel as well as the storage capability of the battery pack. This integration of multiple energy sources in conjunction with the load of the vehicle itself can be achieved if energy can freely and efficiently be exchanged between such sources to the vehicle or any other load.